Sense of humor, too
In his novel "The Mars Underground", he relates the story of how old Viking Orbiter pictures showed the parachute from the failed Soviet Mars-2 lander blowing in the wind, and he works Mars-2 into the story. I was intrigued by the story so I went searching through the Viking photos, and sure enough, I found several frames at the coordinates he gave with a little white speck. The speck really did look like it was moving across the surface from frame-to-frame.
I was pretty pleased with myself, until I looked at several unrelated frames. They also had the white speck. Turns out that there was a mote of dust inside the camera floating around. He got me good. I wonder how many other people fell for it?